High-field NMR spectroscopy has been shown to be an extremely powerful tool for chemical, biochemical, and biomedial research, and a number of such instruments are now in use in the United States. THe inherently low sensitivity of NMR even at high magnetic fields means that large samples, which may also need to be isotopically enriched (13C, 15N), must be used, especially if it is desired to study nuclei having low gyromagnetic ratios in living organisms or cells. There is currently no wide-bore high-field NMR spectrometer which is suitable for such work in the Lost Angeles area to our knowledge. This proposal is for the purchase of such as instrument to be used by a large base of research workers investigating a wide variety of problems in chemistry, biochemistry and cell biology. Many of these problems are health-related since they involve compounds or processes of medical importance. Problems being investigated by the prime user groups include (1) an investigation of the pathways of ammonia assimilation in Neurospora crassa, (2) a study of the pathways of arginine degradation in Klebsiella aerogenes, (3) the possible association of vacuolar arginine with polyphosphates in N. crassa, (4) studies of complexation phenomena as models of enzymic catalysis, biological control mechanisms, immunological response, processing of genetic information, inophore transport, and drug action, (5) elucidation of the molecular mechanism of visual transduction, (6) the mechanisms of voltage-dependent conformational transitions in membrane proteins, (7) the total synthesis of complex natural product, (8) determination of the solution conformation of drugs and their interactions with DNA, and (9) investigations of the reversible reactions that occur at enzyme catalytic sites. The role of NMR in these investigations is outlined in the accompanying research description.